Fluorescent Tubes Require Upkeep, But It`s Worth The Effort

February 21, 1986|By Bernard Gladstone, New York Times News Service.

Fluorescent lighting is not only much more energy efficient than incandescent lighting--a 40-watt fluorescent tube will give five or six times as much light as a 40-watt incandescent bulb--but fluorescent tubes usually last five to six times longer.

Fluorescent fixtures are more complicated than incandescent units, so they occasionally require repair. In many cases it is simply a matter of replacing the tube, but sometimes this alone is not enough to make the fixture work properly.

With incandescent lights, 110-volt house current goes directly into the bulb. A high-resistance filament on the inside starts to glow, giving off the light that we see. Because a great deal of heat is generated, a high percentage of the current used to generate this heat is wasted. In fluorescent tubes, the household current is fed to a built-in transformer called a ballast. The ballast steps up the voltage and feeds it into the gas-filled fluorescent tube that has a phosphorescent coating on the inside. The current causes the tube to glow and throw off light without much heat.

One older style of fluorescent tube is a preheat type with a separate, replaceable starter, a small, can-shaped device that fits under the bulb at one end. A newer rapid-start tube does not have a separate starter. Both have a ballast on the inside that supplies power, and both use tubes that have two pins at each end that fit into special sockets on the fixture.

The preheat type usually takes a second or two to come on and may blink once or twice before staying on. The rapid-start type comes on almost immediately and does not blink (if it is working properly). The starter circuit in this type is built into the ballast.

When a fluorescent fixture fails to light, first check the fuse for that circuit. Make sure that it has not blown and the circuit breaker has not tripped. After this, twist the bulb back and forth a couple of times to see it is firmly seated. If it still doesn`t light, remove it completely. To do this, give it a quarter turn in either direction, then slide the two pins at each end straight out of their sockets.

When the tube is out, wipe the pins clean with fine steel wool and dust the sockets. Replace the tube by sliding the pins at each end into their sockets, then give the tube a quarter-turn in either direction. If the tube still doesn`t light, take it out again and replace it with a new one or with one that you know is working.

If the fixture has a replaceable starter, it could be that it needs a new one. Any time you replace a tube you also should replace the starter.

To replace the starter, you first must remove the tube because the starter can is mounted under one end. Twist the starter counterclockwise a quarter-turn and pull straight out. To install the new one, push in and give it a quarter-turn in a clockwise direction. The new starter must be the same capacity as the original (this is stamped on the outside). With the new starter in place, you can replace the bulb that you know is good, then try again.

If the fixture still does not light, the trouble is probably inside the fixture--either a loose wire or a defective ballast. Turn off power to that fixture, then remove the tube and the metal cover that conceals the wiring and the ballast (screws at each end must be removed to take the cover off).

Check all the wires to see if the twist-on connectors are tight. Tighten those that seem loose or have come apart, then try the light again. If the problem is not in the wiring, the ballast is probably defective.

To remove the ballast, first disconnect the wires leading to it. Before you do this, use pieces of masking tape to mark where each wire goes, then disconnect it by twisting off the solderless connectors. In some cases it may be necessary to cut the wires. If so, strip off the insulation from the ends of the wires so that you can connect them to the new ballast after it is installed. Most ballasts are held in place by two screws, one at each end.

When purchasing a new ballast (sold in electrical-supply and hardware stores) be sure to get one of the same rating.

Sometimes a fluorescent tube will light but continue to flicker. If the tube is a new one, the flickering should disappear after it has been in use for a few hours.

If the tube is not new, the tube may not be seated properly in its sockets. Take it out and clean the pins at each end by rubbing them with fine steel wool. Make sure the screws that hold the sockets in place are tight, then replace the tube. The pins must be firmly seated; twist the tube back and forth a few times while pressing it in.

There are three other possible reasons for constant flickering: A new starter is needed; the tube is aging and needs replacing; or the temperature is too low. Most fluorescents will flicker or be hard to start when temperatures drop below 60 Fahrenheit. If you can`t warm the room, try installing a special low-temperature starter or ballast.

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